The Sars-CoV-2 virus can persist in the lungs for up to 18 months after infection, according to new research.
The Sars-Cov-2 virus can remain in the body for up to two years – Photo Archive
A study conducted by the Pasteur Institute, in collaboration with another French public institute, on lung cells from animals, shows that the SARS-CoV-2 virus is found in the lungs of certain people for up to 18 months after infection.
One to two weeks after contracting COVID, the SARS-CoV-2 virus generally becomes undetectable in the upper respiratory tract.
Moreover, research published in the journal Nature Immunology suggests that its persistence appears to be linked to a failure of innate immunity, the first line of defense against pathogens.
Viral reservoirs
It is already known that some pathogens persist in the body in a discreet and undetectable way after causing an infection, they remain in what are called “viral reservoirs”, according to scientists.
This is also the case with the HIV virus, which remains latent in certain immune cells and can reactivate at any time, but it can also be the SARS-CoV-2 virus, which causes COVID-19.
“We observed that inflammation persisted for long periods of time in primates that were infected with SARS-CoV-2. Therefore, we suspected that this could be due to the presence of the virus in the body,” said Michaela Muller-Trutwin, head of the HIV, Inflammation and Persistence Unit at the Institut Pasteur.
Scientists in France analyzed biological samples from animals that had been infected with the virus.
Initial results of the study indicate that the viruses were found in the lungs of some people six to 18 months after infection, even though the virus was undetectable in the upper respiratory tract or blood.
The Omicron strain appears to leave a smaller amount of persistent virus in the lungs than the original SARS-CoV-2 strain.
“We were very surprised to find viruses in certain immune cells – the alveolar macrophages – after such a long time and when the usual PCR tests were negative. (…) Furthermore, we cultured these viruses and could observe, with the tools we developed to study HIV, that they were still able to reproduce,” said Nicolas Huot, first author of the study and researcher at the HIV, Inflammation and Persistence Unit of the Institut Pasteur.
The role of Natural Killer cells
In fact, the researchers also studied the “Natural Killer” cells, responsible for immunity.
“The cellular response of innate immunity, which is the body’s first line of defense, has been little studied so far in the case of SARS-CoV-2 infections. However, Natural Killer cells have long been known to play an important role in controlling viral infections,” said Muller-Trutwin
According to the study, in some animals, macrophages infected with SARS-CoV-2 become resistant to destruction by Natural Killer cells, while in others, adaptive Natural Killer cells are able to adapt to the infection and destroy the resistant cells, in in this case macrophages.
This can explain the presence of viral reservoirs. While people with low or no virus long-term had production of adaptive Natural Killer cells, people with higher levels of virus had a reduction in the activity of these types of cells, the researchers say.
2023-12-11 12:29:35
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